The Grammy Award-winning pop singer will attend a rally organized by Servicemembers Legal Defense Network on Monday in Deering Oaks Park, near the University of Southern Maine’s Portland campus.

Lady Gaga is expected to stand alongside veterans who were discharged because of the policy, which prohibits service members from revealing if they’re gay, the group said. The policy also bars military recruiters from asking about people’s sexual orientations.

A proposal to repeal the “don’t ask, don’t tell” policy is attached to the defense authorization bill, which Democrats will try to bring to a vote this week.

Democrats need 60 votes on Tuesday to cut off debate and proceed to the bill, again putting Republican Sens. Olympia Snowe and Susan Collins of Maine in the role of casting what could be deciding votes in the Senate, said Trevor Thomas, spokesman for Servicemembers Legal Defense Network.

“We need the support of Collins and Snowe and the best way to get it is to be able to be in their backyard,” Thomas told The Associated Press.

Collins previously voted for a provision to repeal the “don’t ask” policy in the Armed Services Committee, but she wants “a full and open debate” on the defense authorization bill as well as the ability for Republicans to offer amendments, said her spokesman, Kevin Kelley.

Snowe has not decided how she’ll vote on Tuesday, a spokesman said Monday.

Lady Gaga recently called on Senate Majority Leader Harry Reid to repeal the policy during an interview with talk show host Ellen DeGeneres. Gaga is known for her wacky wardrobe and catchy hits, including “Bad Romance,” “Paparazzi” and “Poker Face.”